Technology is moving forward at a rapid pace, and we do our best to deliver the inside info on these new technologies to our readers as quickly and effectively as possible. When we heard about these new ready-to-assemble piston kits coming from Mahle, we had to get a closer look.
Under normal circumstances, pistons are far from being ready to install when you receive them. This is because of the fine-tuning most custom parts require before actually being installed into a working engine. Whether it be machine work on the valve notches, simple smoothing of sharp edges, or weight and balance machining, pistons normally see some type of effort and input prior to getting hung on the rods. These processes are not necessary with the new PowerPak piston kits from Mahle.
As various types of engine coatings have become more common, this step is elbowing its way into the regular list of "must-do" items accompanying new pistons. Many builders have seen the increased compression ratios possible with coated parts, and the benefits of friction-reducing coatings on piston skirts is well-documented. Sharp builders have learned how critical temperature control inside the combustion chamber is, and coated pistons (along with coated chambers and valves) go a long way toward keeping detonation at bay and making each pistons contribution to the torque at the flywheel more consistent from cylinder to cylinder.
Mahle pistons are much more common in European racing, and they are making a bold statement in domestic race markets as well. Their precision manufacturing and complete "ready to run" status is finding favor with race engine builders, and now this level of convenience is being made readily available to street enthusiasts as well.
Mahle's new piston kits are pre-weighed, completely finished, treated with both friction reducing and thermal barrier coatings, and shipped with pre-fitted pins. They are literally ready to be washed, have the rings (which are included) installed, and be hung on the rods ready for installation.
If you compare prices, you'll find Mahle's kits are more expensive than other manufacturers parts. When considering the time saved by not having to go through a lengthy preparation procedure prior to installation, and not having to wait for the parts to get coated, money can actually be saved in the long run. Mahle has begun releasing kits for the most popular domestic applications, and we took a look at one of its typical small-block Chevy kits; this one for a .040-inch overbored 350 or 327 (4.040-inch bore size).
The phosphate coating on the piston top and the Grafal anti-friction coating on the piston skirts are applied to the finished pistons by Mahle, so they're ready to go... |
...If piston mods are absolutely necessary (to account for valve clearances etc.), there should be no adverse effects in the modified areas where the coating must be removed. We feel these pistons are perfect for milder engines being built to deliver good power for the long haul... |
...If you bracket race, hit a few track days per year, or are considering a part-time nitrous system, these pistons should fill the bill perfectly. |
Mahle's PowerPak pistons are made from a low-expansion alloy, which allows for tighter piston-to-wall clearances than we're used to. Mahle recommends .0025-.0030-inch for small-blocks, and .0035-.0040-inch for big-blocks. Nitrous, supercharged, and severe duty applications may want an additional .001-.003-inch, and it's always better to be a little loose than a little tight. |
Each Mahle piston is designed in a 3-D CAD system to ensure minimal weight and maximum durability. Lighter reciprocating components make for quicker revs and less work to move, which translates into horsepower... |
...Mahle uses this same equipment to design and manufacture OEM pistons for Chevy's Corvette and Dodge's Viper, in addition to Formula 1 and NASCAR. |
The rings engineered to work with Mahle's pistons are specifically designed to improve seal and fit correctly within the grooves. They are a file-to-fit design, and each ring must be fitted to each specific cylinder. This extra effort guarantees optimal ring gaps, and these filing operations can also be accomplished at home. We also like the foolproof packaging, so rings cannot be mixed up. |
Ring thicknesses are smaller than we're used to, checking in at 1.5mm on both the top and second rings, with a 3.0mm oil control ring set. You can also see the ring top surfaces are clearly marked for easy installation. We saw many rings of these thicknesses in last year's Engine Masters Challenge, and the minimal friction surely contributed to the high scores posted by the builders who ran them. If the gaps are correct, oil control is not an issue. |
Mahle's new PowerPak piston kits are pre-weighed, and the pins are pre-fitted. The pins are also of top-quality, and are a full-floating design to minimize friction even further. Full floaters are just plain easier to assemble too, since no oven or press is required to install the pins. If you're building an engine at home, these are valid points when it comes to selecting pistons. |
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